This investigation seeks A) to describe the hemodynamic factors that affect the pulmonary fluid compartments of the normal lung and the high altitude lung; B) to study the physiologic mechanisms responsible for the arterial hypoxemia associated with myocardial infarction; C) to study the effects of morphine sulfate on the pulmonary vasculature and D) to describe the effects of positive pressure breathing on the pulmonary fluid compartments. A modification of the double indicator dilution technic using room temperature physiologic saline and indocyanine green dye will be used.